The present invention relates to a method for changing a material from a starting material to a subsequent material in an extrusion device and an extrusion plant for the production of an extrusion product.
Basically extrusion plants are known. They are used in order to produce extrusion products. Such extrusion products can be injection moulding products, particularly film products. One possibility of extrusion products are so called blown films. Hereby, the extrusion device is normally equipped with at least one extruder in a barrel extruder. This extruder is supplied with extruder material. The corresponding material which should be used for the current formulation can also be described as starting material. For the supply of starting material normally supply devices, like for example a storage tank and/or a storage scale are known. These serve for the provision of a proportioned supply of starting material to the barrel extruder.
With this known extrusion plants after termination of the production of a first extrusion product and prior to the start of the production of a second extruder product with different stocks of material a change of material has to occur. This means that instead of the used starting material a subsequent material is supplied to the extrusion device. This change of material is performed entirely manual with known extrusion plants. Hereby, after termination of the performance of a first formulation during the production of a first extrusion product frequently a complete cleaning of the extrusion plant is performed. It is also known that with known extrusion plants during the transition period the new subsequent material is filled into the storage tanks or the storage scales. After a certain transition period the subsequent material has completely replaced the starting material from the storage tank, the storage scale and the extruder. During this transition period the produced extrusion product is however not equipped with defined properties according to the adjusted formulation. Accordingly, the produced extrusion product during this transition period is waste. Disadvantageously with this method are the produced waste and the high time requirement during the manual performance of the change of materials. Alternatively performed complete internal cleanings of the extrusion plants are likewise time consuming and produce high cost and downtimes.